Method for producing a shaft comprising stop caps device containing one such shaft

ABSTRACT

The invention relates to a method to manufacture a shaft ( 22 ) as well as a device containing such a shaft ( 22 ), in particular an armature shaft ( 22 ) of an electromotive drive ( 10 ), which is held by at least one shaft mounting, whereby a curved, rounded stopping tip ( 40 ) that can support itself on an axial stopping face ( 32, 34 ) is formed at least one fore part ( 28, 30 ) of the shaft ( 22 ) by means of material displacement.

RELATED APPLICATION

This application is a 35 USC 371 of International Application No.PCT/DE03/01599, filed May 19, 2003.

BACKGROUND OF THE INVENTION

The invention relates to a method to manufacture a shaft with roundedstopping tips as well as a device containing such a shaft, as well as adevice to manufacture such a shaft in accordance with the species of theindependent claims.

With WO 01/65 668, a device has become known that is used, for example,to move window panes, sun roofs or seats. In order to avoid undesiredlongitudinal play in the armature shaft, it is proposed there that adamping rubber piece be pressed into a recess of the housing on at leastone of the fore parts. The armature shaft features a rounded stoppingtip on one of its fore parts, which is supported against a stop disk,which is pressed in turn against the damping rubber piece.

This type of rounded stopping tip is normally manufactured by means ofturning on a lathe or grinding in a machining process on the fore partof the armature shaft before installation of the electric motor.Afterwards, the rounded stopping tip is polished in order to achieve ahigh surface quality and then hardened so that the rounded stopping tipdoes not get damaged when the electric motor is assembled. This methodis very labor intensive and expensive.

SUMMARY OF THE INVENTION

The method in accordance with the invention has the advantage that ahigh-quality and wear-resistant surface is created when forming arounded stopping tip by means of cold forming in one work step. It ispossible to completely dispense with the process steps of polishing andhardening since, on the one hand, the surface is created in one workstep by means of material displacements and, on the other hand, thisprocedural step can be conducted in a favorable manner after assembly ofthe armature.

Advantageous further developments of the method are possible. In termsof manufacturing techniques, it is especially simple to perform thematerial deformation by means of a roller-burnishing process in which arotating rolling tool rolls on the shaft. A very dimensionally accurate,rotationally symmetrical rounded stopping tip can be manufactured as aresult. In addition, a long tool service life and a smooth work piecesurface are achieved because of the rolling off of the tool.

To manufacture the rounded stopping tip on an assembly line, it isadvantageous to secure the shaft with a gripper and adjust a rotatingdeformation roller with an axial working surface. A radius is thenformed on the fore part of the shaft because of the tilting of the axisof the deformation roller, vis-à-vis the shaft axis.

The material deformation takes place during the tilting of thedeformation roller on a spiral-shaped line so that with increasedtilting of the material of the shaft there is continuous displacement inthe radial and axial direction. This continuous flow process creates avery smooth and hard surface of the rounded stopping tip.

Due to the selection of the crossing point of the shaft axis with theaxis of the deformation roller when tilting the same, the radius of therounded stopping tip can be produced in accordance with the requirementsof the axial mounting of the shaft. As a result, any desired radii canbe formed with one working surface of the deformation roller. Beforeassembly of the armature shaft on its fore part, a phase ismanufactured, through which the diameter of the rounded stopping tip canbe prescribed in connection with the pressing force of the deformationroller against the shaft. The phase guarantees that the shaft materialcan yield during its deformation, thereby reducing deformation volumeand deformation time.

It is favorable not to execute the rounded stopping tip until anadvanced assembly stage of the electric motor after various componentshave already been fixed to the armature shaft since then the surface ofthe rounded stopping tip can no longer be damaged during furtherassembly.

On the other hand, it is advantageous to form the rounded stopping tipbefore rolling a worm on the shaft, since then the worm cannot bedamaged with acceptance into the deformation head during manufacture ofthe rounded stopping tip or when fixing the armature shaft.

A device, in accordance with another embodiment of the invention toadjust movable parts in motor vehicles, has the advantage that acost-effective axial mounting of the armature shaft, which iswear-resistant over long service lives with a surface roughness of therounded stopping tip of less than one micrometer, is realized with therounded stopping tips formed by means of a deformation roller.

A device, in accordance with another embodiment of the invention, hasthe advantage that it can be favorably integrated procedurally into anassembly line due to the axial adjustment and tilting of the deformationroller, vis-à-vis the rotational axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the devices in accordance with the inventionare depicted in the drawing and explained in more detail in thefollowing description. The drawings show:

FIG. 1 A section of a device to adjust movable arranged parts.

FIG. 2 A device to manufacture a shaft according to the method inaccordance with the invention

FIG. 3 An enlarged detail of the rounded stopping tip in FIG. 2.

DETAILED DESCRIPTION

FIG. 1 shows an adjusting drive 10, with a motor 12 and a multiparthousing 16 surrounding a gear 14. The motor 12 is electricallycommutated and features an armature 18, a commutator 20 and a multiplypositioned armature shaft 22, which extends into the area of the gear14. A worm 26, which communicates with a worm wheel 24 via gear toothing25, is arranged on the armature shaft 22. This is supported on the foreparts 28 and 30 of the armature shaft 22 in the longitudinal directionvia stop disks 32 and 34, as well as via a damping rubber piece 36 onthe housing 16, or a portion of the same. A rounded stopping tip 40 isformed on one end 38 of the armature shaft 22 by means of materialdisplacement. The radius 42 of the rounded stopping tip 40 determinesthe size of the surface with which the armature shaft 22 is pressedagainst the stop disk 32. The smaller this surface is, the smaller thefrictional losses; however, wear increases with a diminishing stoppingface. As a result, the radius 42 of the rounded stopping tip 40 isspecified in such a way that a good compromise is achieved between lowfriction and low wear. In addition, such a great tip height of therounded stopping tip 40 is selected via the radius 42 that during theentire service life, the rounded stopping tip 40 does not sink too deepinto the stop disk 32 (which for the most part is manufactured ofplastic), and that the tip edges 41, which delimit the radius 42 of therounded stopping tip 40, touch the stop disk 32.

FIG. 2 depicts the method in accordance with the invention on the basisof a device to manufacture a shaft 22. Several components 44, such as anarmature 18, a commutator 20 or a ring magnet 21 are already pre-mountedon the shaft 22 before the armature shaft 22 is held for example bymeans of a gripper (not shown) having, for example, a pivoted guide bushto receive the shaft 22. The deformation device 50 is composedessentially of a drive 52, which allows a deformation head 54 to rotate.A deformation roller 56 is arranged in the deformation head 54 on acentral rotational axis 58. The deformation head 54 can be fed in theaxially direction 63 by means of an adjusting unit 60 and thedeformation roller 56 can be tilted vis-à-vis the central rotationalaxis 58 of the deformation head 54 via a reversing lever 62. In thisexemplary embodiment, the rotational axis 58 lies congruent with an axis64 of the armature shaft 22. While the deformation head 54 rotatesaround the rotational axis 58, the deformation roller 56 is set againstthe fore part 28 of the armature shaft 22 and the deformation roller 56is tilted vis-à-vis the axis 64 of the armature shaft 22. As a result,the deformation roller 56 touches the armature shaft 22 with an axialworking surface 66 in a punctiform deformation area 68, which during therotation runs in accordance with arrow direction 55 and during tiltingof the working surface 66 in accordance with arrow direction 80 on aspiral-shaped line. In this connection, the material of the armatureshaft 22 is displaced from the axis 64 radially towards the outside andaxially towards the armature 18, whereby a curved surface of a roundedstopping tip 40 is formed on the armature shaft 22. The cold forming ofthe material produces a compression of the surface material andtherefore a surface roughness of less than 1 micrometer.

FIG. 3 shows an enlarged detail of the rounded stopping tip 40 in FIG.2, whereby a phase 70 is manufactured on the armature shaft 22 beforeforming a rounded stopping tip, which phase permits a correspondingclearance zone 71 for the material deformation by the deformation roller56. The phase 70 in the exemplary embodiment is executed in two stages,but can just as well be manufactured as a continuous phase 70. Theradial extension 72 of the phase 70 specifies, within certain limits andin connection with the to-be-applied application force of thedeformation roller 56, a diameter 74 (of 3 to 4 millimeters for example)of the rounded stopping tip 40 since the material cannot be reformed toany width in the clearance zone 71 of the phase 70. The curvature of thesurface of the rounded stopping tip 40 has a radius 76, which is createdby tilting the axial working surface 66 of the deformation roller 56around a tilting point 78 on the axis 64 of the armature shaft 22 inaccordance with arrow direction 80. In this connection, the deformationroller 56 is tilted in accordance with arrow direction 80, e.g., over anangle range 82 from −5° or +20°. The radius 76 is usually smaller thanthe swivel radius of the deformation roller 56 since the shaft 22 issubject to axial tension during the deformation process and ispermanently pressed back.

In another variation of the method, a rotating deformation roller 56 isattached in a stationary manner and the fore part 28 of the shaft 22 ispressed against the working surface 66 of the deformation roller 56 andtilted vis-à-vis the shaft axis 64 by a tilting angle 82.

In another alternative of the method, the shaft 22 rotates around itsaxis 64 and is set against the stationary working surface 66 of thedeformation roller 56 and either the armature shaft 22 or thedeformation roller 56 is tilted by a tilting angle 82.

In the case of these variations of the method in accordance with theinvention, what matters is that the fore part 28 of the shaft 22 isrotated against a working surface 66 and these two surfaces arecontinuously tilted against one another. As a result, a high-qualitysurface of a rounded stopping tip 40 is generated by means of materialdisplacement, which rounded stopping tip can be formed on one or bothends 38, 39.

In another exemplary embodiment, as the method of material displacement,a curved stamping tool is moved under pressure against the fore part 28,30 of the shaft 22, whereby this does not necessarily have to be a purerotational movement.

It is preferred that the method in accordance with the invention be usedfor manufacturing an electric gear/drive unit, but it is not limited tothis. The invention also includes individual features of the exemplaryembodiments or any combination of the features of the differentexemplary embodiments.

1. Method to manufacture an armature shaft (22) of an electromotivedrive (10), wherein a curved, rounded stopping tip (40) is formed on atleast one fore part (28, 30) of the shaft (22) by means of materialdeformation, which rounded stopping tip can support itself on an axialstopping face (32, 34), wherein the material deformation to form thestopping tip (40) is executed by means of a deformation roller (56),while the armature shaft (22) is held by means of a gripper.
 2. Methodaccording to claim 1, characterized in that the material deformation toform the rounded stopping tip (40) is executed by means of a deformationroller (56).
 3. Method according to claim 2, characterized in that oneworking surface (66) of the deformation roller (56) and the fore part(28, 30) of the shaft (22) rotate relative to one another, the fore part(28, 30) and the working surface (66) are adjusted axially relative toone another and the fore part (28, 30) and the working surface (66) aretilted relative to one another.
 4. Method according to claim 3,characterized in that the material of the shaft (22) is induced to flowaxially and/or radially via a variable adjustment of the fore part (28,30) with respect to the working surface (66), thereby generating acompressed, smooth surface of the rounded stopping tip (40).
 5. Methodaccording to claim 3, characterized in that a radius (76) is formed onthe rounded stopping tip (40), which is determined by the distance ofthe working surface (66) to a tilting point (78) on an axis (64) of theshaft (22).
 6. Method according to claim 1, characterized in that atleast one phase (70) is manufactured on the shaft (22) before forming atleast one rounded stopping tip (40).
 7. Method according to claim 1,characterized in that to begin with at least one component (44, 18, 20,21), in particular an armature (18) of an electromotive drive (10), ismounted on the shaft (22) and afterwards at least one rounded stoppingtip (40) is formed.
 8. Method according to claim 1, characterized inthat the forming of at least one rounded stopping tip (40) takes placebefore the forming of a worm (26) on the shaft (22).
 9. Method accordingto claim 4, characterized in that a radius (76) is formed on the roundedstopping tip (40), which is determined by the distance of the workingsurface (66) to a tilting point (78) on an axis (64) of the shaft (22).10. Method according to claim 2, characterized in that at least onephase (70) is manufactured on the shaft (22) before forming at least onerounded stopping tip (40).
 11. Method according to claim 3,characterized in that at least one phase (70) is manufactured on theshaft (22) before forming at least one rounded stopping tip (40). 12.Method according to claim 4, characterized in that at least one phase(70) is manufactured on the shaft (22) before forming at least onerounded stopping tip (40).
 13. Method according to claim 5,characterized in that at least one phase (70) is manufactured on theshaft (22) before forming at least one rounded stopping tip (40). 14.Device to adjust moveable parts belonging to a motor vehicle, with ahousing (16), an electric driving motor (12) featuring an armature shaft(22) and a worm gear (14), which gear is effectively connected with thedriving motor (12) via the armature shaft (22), whereby the armatureshaft (22) is manufactured by forming a curved, rounded stopping tip(40) on at least one fore part (28, 30) of the shaft (22) by means ofmaterial deformation, which rounded stopping tip can support itself onan axial stopping face (32, 34), wherein the material deformation toform the stopping tip (40) is executed by means of a deformation roller(56), while the armature shaft (22) is held by means of a gripper,characterized in that a rounded stopping tip (40) that supports itselfwith respect to the housing (16) via a stopping face (32, 34) is formedon at least one fore part (28, 30) of the armature shaft (22) by meansof material displacement.
 15. Device to manufacture an armature shaft(22) of an electromotive drive (10), the device comprising a gripper forholding the armature shaft (22), characterized in that the device (50)features a deformation head (54) rotating around a rotational axis (58)with a deformation roller (56) and at least one adjusting unit (60, 62)for axial and/or radial adjustment and tilting of the deformation roller(56) with respect to the rotational axis (58).